1. Field of the Invention
The invention relates to a cooler that uses a liquid coolant.
2. Description of Related Art
In a cooler that uses a liquid coolant, a temperature of the coolant may be used to control the cooler (for example, Japanese Patent Application Publication No. 2011-172406 (JP 2011-172406 A) and Japanese Patent Application Publication No. 2012-52504 (JP 2012-52504 A). JP 2011-172406 A discloses a cooler for an inverter of an electric vehicle. Water is used as the coolant. An abnormality in the cooler is detected on the basis of a temperature difference between a water temperature (a coolant temperature) and a temperature of the inverter. Further, JP 2012-52504 A discloses an engine cooler. In this technique, an engine output is calculated from an engine rotation speed and an output torque. A target water temperature (a target coolant temperature) is set on the basis of the calculated engine output. A pump and a fan of the cooler are then controlled so as to realize the set target water temperature.
Japanese Patent Application Publication No. 2010-216386 (JP 2010-216386 A) also discloses an engine cooler. JP 2010-216386 A discloses a technique for estimating a water temperature in a position removed from a water temperature sensor (a coolant temperature sensor). In this technique, the water temperature in a predetermined position removed from a temperature sensing portion of the water temperature sensor is estimated using a parameter that correlates with a difference between an amount of heat radiation from the engine in the temperature sensing portion and an amount of heat radiation from the engine in the predetermined position.